When drilling boreholes, such as when drilling an oil, gas or water well, drilling fluids are commonly used. Drilling fluids, which are also referred to as drilling muds (hereinafter collectively “drilling fluids”), may provide one or more functions during the drilling process such as, for example, to provide lubrication to the drill bit, to provide pressure in the well bore, and to provide a transport mechanism to remove drill cuttings that are produced by the drilling of the borehole.
Drilling fluids are expensive and closely monitored and analyzed during the drilling process to ensure that the chemical and physical characteristics of the drilling fluids are maintained at desired levels during the drilling process. The desired characteristics may change at different depths of the borehole and as geographic formations vary along the borehole. Drilling fluids are often recycled and reused because of their significant cost.
Drilling fluids may contain hazardous or dangerous chemicals, such as petroleum, based drilling fluids. As such, the use, disposal, handling and recycling of drilling fluids present significant environmental concerns.
As drilling fluids exit the borehole during the drilling process, they contain drill cuttings, which include the rocks, sands, materials, dirt, and the like that were removed to create the borehole. As such, the drill cuttings are coated and mixed with the drilling fluids. This may present significant environmental issues when attempting to separate the drill cuttings from the drilling fluids so that the drilling fluids can be recycled and reused, or so that the drill cuttings can be safely disposed.
The separation of gold (or other minerals or elements) from slurries during certain mining processes also presents technical, environmental and economic concerns.